1. Field of the Invention
The present invention relates to an assembled light-guiding module, and particularly relates to an assembled light-guiding module with high light-guiding efficiency.
2. Description of Related Art
The design of a conventional light pipe includes the following relevant factors:
1. Light Entrance Surface:
Referring to FIGS. 1A and 1B, when the projected direction of light beam (L10 or L20) is vertical to the light entrance surface, then the reflective rate of the light beams (L10, L20) are at their lowest. The light entrance surface S1 of the light pipe P1 as shown in FIG. 1A is usually a planar surface due to the cost of molding. Therefore, considering that if the entrance angle of the light beam L11 gets larger, then most of energy of the light beam L11 will not enter the light pipe P1 due to reflection. On the other hand, if the light entrance surface S2 of the light pipe P2 is a concave hemispherical surface as shown in FIG. 1B, then most of the energy of the light beam L21 will enter the light pipe P2; yet as mentioned before, the cost for molding increases correspondingly.
2. Light Exiting Surface:
Referring to FIG. 1C, the light exiting surface S3 of the light pipe P3 is usually a planar surface due to the cost of molding. The light exiting surface S3 is far away from the light source, so that the projected directions of the light beams are approximately vertical to the light exiting surface S3. Hence, most of the energy of the light beam L3 would exit from the light pipe P3.
Referring to FIG. 1D, when the light exiting surface S4 of the light pipe P4 is a concave hemispherical surface, most of the energy of the light beam L4 will not exit out of the light pipe P4 due to the total reflection principle. However, the molding cost is increased.
3. Light Pipe Material:
In generally, the light pipe is made of high density translucent material, and the appearance of the light pipe is smooth. Therefore, the light beams are totally reflected in the light pipe until light beams exit out of the light pipe□ unless the projected directions of the light beams are changed by small concave or convex points.
4. Light Reflecting Microstructure:
In consideration of the molding cost, the microstructure C6 as shown in FIG. 1F is formed by a mold with concave microstructure. Hence, the manufacture of the microstructure C6 in FIG. 1F is easier than that of the microstructure C7 in FIG. 1G.
Comparing FIG. 1E with FIG. 1F, the projected directions of the light beams L51, L52 are changed by the sawtooth microstructure C5, and then the light beams L51, L52 immediately exit out of the light pipe P5. The projected directions of the light beams L61, L62 are changed by the sawtooth microstructure C6 and then the light beams L61, L62 immediately exit out of the light pipe P6. The projected direction of the light beam L53 is changed by the sawtooth microstructure C5 and then the light beam L53 that is reflected between the light beams L51, L52 immediately exit out of the light pipe P5. On the other hand, the light beam L63 is totally reflected in the light pipe P6 and does not exit out of the light pipe P6 immediately.
Comparing FIG. 1E with FIG. 1G, the projected directions of the light beams L71, L72, or L74 are changed by the sawtooth microstructure C7 and then the light beams L71, L72, or L74 exit out of the light pipe P7. The projected directions of the light beams L51, L52, or L54 are changed by the sawtooth microstructure C5 and then the light beams L51, L52, or L54 exit out of the light pipe P5. However, the positions of changing the projected directions of the light beams L71, L72 or L74 from the light entrance surface are farther than the positions of changing the projected directions of the light beams L51, L52 or L54 from the light entrance surface. The light beam L75 is totally reflected in the light pipe P7 and would not exit out of the light pipe P7 immediately. The projected direction of the light beam L55 is changed by the sawtooth microstructure C5 before the projected direction of the light beam L54 is changed, and then the light beam L55 exit out of the light pipe P5.
Comparing, FIG. 1F, with FIG. 1G, the numbers of the sawtooth microstructures C6, C7 are the same. Since the sawtooth microstructures C6 are extends out of the light pipe P6, the effective reflective area of the sawtooth microstructures C6 is smaller than that of the sawtooth microstructures C7. Hence, the light-exiting efficiency of the light pipe P7 is better than that of light pipe P6. However, the cost of the light pipe P7 is also higher than that of light pipe P6.
5. The Reflective Light Beams can be Fully Utilized on Light Exiting Surface:
The light exiting surface indicates the plane on which the reflective microstructures has been formed or the corresponding surface that is parallel to the plane on which the reflective microstructures has been formed.